Toothbrushes and the practice of brushing teeth are widely spread throughout the world. In the last decades, the use of electrical toothbrushes has become more and more common, especially in the developed world.
Electrical toothbrushes come in many shapes and forms, but are mostly based on the same principle of a motor operating the movement of a shaft in at least one direction. Such electric toothbrushes are disclosed in e.g. U.S. Pat. No. 5,974,615, EP-A1-0 790 809 or EP-A1-0 862 390.
Mouth showers or mouth wash devices are also known in the art. Mouth wash devices have been commonly used in since the late 1970'ies and early 1980'ies. An example of such devices is found in U.S. Pat. No. 4,793,332, wherein the use of a multi jet spray mouth wash device is disclosed.
Some attempts have been made to integrate the two into a device that includes both a brushing part and a water jet. WO2006/041920 discloses an electrical toothbrush device comprising a water jet nozzle. However, this design uses an internal mix of air and water, resulting in unreliable water flow rates, or the need of a complex water pump.
Additionally, some toothbrushes have been disclosed (e.g. in WO2008/155025), wherein the brush head comprises an outlet or channel to dispense toothpaste.
Internally mixed air water jet for cleaning tooth is also known in the art. U.S. Pat. No. 5,820,373 discloses a periodontal pocket cleaning device for the prevention of periodontal disease, which is least liable to cause injury to the periodontal pocket, which can be used at any place without limiting the place of its use, which is able to obtain a stabilized atomized jet without being influenced by the height position of the handy probe, and which is available at a low cost. Also U.S. Pat. No. 5,593,304 discloses a dental apparatus includes a handpiece graspable at one end by a user, and a head at the opposite end of the handpiece including a single nozzle, or a pair of nozzles connectible to a source of liquid, a gas, and/or powder.
One of the problems encountered when integrating a mouth wash device with a toothbrush is that the mouth wash devices are intended to rinse the mouth, rather than for active cleaning, and therefore do not provide suitable cleaning.
Another problem is that while, water is appreciated for washing or rinsing the mouth it is not very convenient when brushing teeth, as toothpaste is then flushed away and while the accumulation of water in the mouth is not generally appreciated by the consumer.
The problem associated with internally mixed air water jet is that the cleaning performance is not up to the mark and the liquid flow is affected by the air-pressure due to the non-separation of the air and water nozzles opening which is not desirable.
A process for cleaning teeth using a device that incorporates a water jet for cleaning teeth remains to be desired, especially a single device that can be employed to clean teeth and reliably deposit material onto teeth.
It is therefore an object of the present invention to provide a process for cleaning tooth with an electrical toothbrush device providing improved cleaning by means of an externally mixed air-water jet wherein the water dosing is not influenced by the air pressure.
It is a further object to provide such improved cleaning while avoiding the use of a large volume of water.
It is a further object of the invention to provide improved removal of plaque, particles, and colour from teeth; especially from the inter-proximal areas of teeth.
It is yet a further object to provide a process for cleaning teeth using a device that can reliably deliver a predetermined amount of liquid, preferably comprising a benefit agent.
There are many methods that have been reported for cleaning dental surfaces, for instance mechanical/physical methods like scrubbing, buffing, abrasion, ultrasonication or use of chemical methods such as use of surfactants, solvents, acids, alkalis, bleaches and enzymes, for instance included in a toothpaste formulation.
In our co-pending application PCT/EP2009/050869 (published as WO2009/103595), a cleaning device is disclosed that comprises a novel kind of air/water jet and methods for using the same for cleaning substrates, such as fabric articles.
Surprisingly it has been found that a tooth brush device, comprising an air/water jet, wherein the air and water are mixed outside the nozzle(s), provides improved cleaning of dental surfaces, including inter-proximal areas, with low usage of water.